1. Field of the Invention
The present invention relates to a magnetic storage apparatus used as an external storage apparatus of an information processing apparatus such as a personal computer, and more particularly to a storage apparatus having an electromagnetic shield member for shielding against the outside.
2. Description of the Related Art
A magnetic storage apparatus such as a hard disk apparatus is used, for example, as an external memory apparatus of an information processing apparatus such as personal computer. In particular, a small-sized hard disk apparatus having a 1.8 inch disk is built in the body of the information processing apparatus.
An outer casing of an information processing apparatus such as a personal computer is normally made of an electrically insulating material such as a resin material. However, internal members of the apparatus are formed of a metallic material such as aluminum alloy in order to attain electromagnetic shield effects against the outside. A casing of a small-sized hard disk apparatus situated within the information processing apparatus is formed of a metallic material such as aluminum alloy.
As is shown in FIG. 7, the body of the small-sized hard disk apparatus comprises a box-like casing 1 and a top cover member 2. The casing 1 includes a side portion 1a and a bottom portion 1b, and, as shown in FIG. 9, a top area of the casing 1 is opened. The casing 1 accommodates a driving mechanism for driving the hard disk apparatus, as shown in FIG. 9. The driving mechanism comprises a disk 5, a rotating mechanism 8 for supporting and rotating the disk 5, a head actuator 6 for moving a head in the radial direction of the disk 5, and a voice-coil motor 7 for driving the head actuator 6.
The top cover member 2, like the casing 1, is made of a metallic material such as aluminum alloy, and the top cover member 2 is a thin plate, as shown in FIG. 10. The top cover member 2 forms a top surface of the casing 1, and it is put in contact with the side portion of the casing 1 to cover the opening of the casing 1. The top cover member 2 is fixed to the side portion 1a of the casing 1 by means of screws 9 at predetermined locations, as shown in FIG. 7, thus constituting the top surface of the casing 1. Further, as shown in FIG. 10, a rubber seal member 10 is attached to a peripheral portion of the top cover member 2, which comes in contact with the side portion 1a of the casing 1. When the top cover member 2 is fixed to the side portion 1a of the casing 1, the air-tightness of the casing 1 can be enhanced by the rubber seal member 10. Specifically, as shown in FIG. 8 (a cross-sectional view taken along line A--A in FIG. 7), the gap between the top cover member 2 and the casing 1 is filled with the seal member 10.
A small-sized hard disk apparatus is normally built in the body of an information processing apparatus such as a personal computer. In this case, as shown in FIG. 7, the bottom surface 1b of the casing 1 is provided with four fixing units 3 at predetermined locations, in order to fix the casing 1 in the body of the information processing apparatus. Each fixing unit 3 comprises a bore having a female screw structure mating with a fixing male screw. In the state in which the casing 1 is fixed in the body of the information processing apparatus by means of the fixing unit 3, the driving mechanism in the casing is electrically connected to the information processing apparatus via a connector 4 provided on the casing 1.
When the casing 1 of the hard disk apparatus is mounted within the body of the information processing apparatus, there is a case where the side portion 1a of the metallic casing 1 or top cover member 2 comes in contact with the parts mounted inside the body of the information processing apparatus. In this case, a high-frequency noise current produced, e.g. from a driving circuit for a display of the information processing apparatus may flow into the casing 1 of the hard disk apparatus. The driving mechanism housed within the casing 1 performs processing with low-intensity electric signals by means of the head supported by the head actuator 6. Thus, if the noise current flows into the casing 1, such low-intensity electric signals are influenced by noise. In the worst case, a data read/write error may occur.
In the body of the hard disk apparatus, the gap between the top cover member 2 and the casing 1 is sealed by the rubber seal member 10, as shown in FIG. 8. Since the rubber seal member 10 is electrically insulative, electromagnetic shield effects for preventing incoming of electromagnetic noise cannot be obtained. Thus, the hard disk apparatus may easily be influenced by electromagnetic noise coming from the parts built within the body of the information processing apparatus.